The only pet peeve for me is find and replace performance using regex. I find if I have a file with upwards of 50000 characters and I do a simple newline replace or text substitution on the file, Sublime hangs and does not respond, eventually completes the operation or crashes completely. I've tried the same operations in ultraedit et al and it works in the milliseconds with no problems.

Performance isn't ideal: syntax highlighting data is recalculated after each modification to the buffer, so large find and replaces can be slow. In some cases it can be a big speed gain to switch to using "Plain Text" for the syntax, doing the replacement, then switching back. I realise this isn't great, and there are some things that'll fix it on the todo list, but they aren't scheduled to be done soon.